Commit c924c65f authored by Jens Wiklander's avatar Jens Wiklander
Browse files

tee: implement protected DMA-heap 



Implement DMA heap for protected DMA-buf allocation in the TEE
subsystem.

Protected memory refers to memory buffers behind a hardware enforced
firewall. It is not accessible to the kernel during normal circumstances
but rather only accessible to certain hardware IPs or CPUs executing in
higher or differently privileged mode than the kernel itself. This
interface allows to allocate and manage such protected memory buffers
via interaction with a TEE implementation.

The protected memory is allocated for a specific use-case, like Secure
Video Playback, Trusted UI, or Secure Video Recording where certain
hardware devices can access the memory.

The DMA-heaps are enabled explicitly by the TEE backend driver. The TEE
backend drivers needs to implement protected memory pool to manage the
protected memory.

Reviewed-by: default avatarSumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: default avatarJens Wiklander <jens.wiklander@linaro.org>
parent a6ccb03f

drivers/tee/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -13,6 +13,11 @@ menuconfig TEE 


if TEE



config TEE_DMABUF_HEAPS

	bool

	depends on HAS_DMA && DMABUF_HEAPS

	default y



source "drivers/tee/optee/Kconfig"

source "drivers/tee/amdtee/Kconfig"

source "drivers/tee/tstee/Kconfig"

drivers/tee/Makefile

+1 −0
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0

obj-$(CONFIG_TEE) += tee.o

tee-objs += tee_core.o

tee-objs += tee_heap.o

tee-objs += tee_shm.o

tee-objs += tee_shm_pool.o

obj-$(CONFIG_OPTEE) += optee/

drivers/tee/tee_core.c

+4 −0
Original line number Diff line number Diff line
@@ -1064,6 +1064,8 @@ void tee_device_unregister(struct tee_device *teedev) 
	if (!teedev)

		return;



	tee_device_put_all_dma_heaps(teedev);



	if (teedev->flags & TEE_DEVICE_FLAG_REGISTERED)

		cdev_device_del(&teedev->cdev, &teedev->dev);
@@ -1287,3 +1289,5 @@ MODULE_AUTHOR("Linaro"); 
MODULE_DESCRIPTION("TEE Driver");

MODULE_VERSION("1.0");

MODULE_LICENSE("GPL v2");

MODULE_IMPORT_NS("DMA_BUF");

MODULE_IMPORT_NS("DMA_BUF_HEAP");

drivers/tee/tee_heap.c

0 → 100644
+500 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/*

 * Copyright (c) 2025, Linaro Limited

 */



#include <linux/dma-buf.h>

#include <linux/dma-heap.h>

#include <linux/genalloc.h>

#include <linux/module.h>

#include <linux/scatterlist.h>

#include <linux/slab.h>

#include <linux/tee_core.h>

#include <linux/xarray.h>



#include "tee_private.h"



struct tee_dma_heap {

	struct dma_heap *heap;

	enum tee_dma_heap_id id;

	struct kref kref;

	struct tee_protmem_pool *pool;

	struct tee_device *teedev;

	bool shutting_down;

	/* Protects pool, teedev, and shutting_down above */

	struct mutex mu;

};



struct tee_heap_buffer {

	struct tee_dma_heap *heap;

	size_t size;

	size_t offs;

	struct sg_table table;

};



struct tee_heap_attachment {

	struct sg_table table;

	struct device *dev;

};



struct tee_protmem_static_pool {

	struct tee_protmem_pool pool;

	struct gen_pool *gen_pool;

	phys_addr_t pa_base;

};



#if IS_ENABLED(CONFIG_TEE_DMABUF_HEAPS)

static DEFINE_XARRAY_ALLOC(tee_dma_heap);



static void tee_heap_release(struct kref *kref)

{

	struct tee_dma_heap *h = container_of(kref, struct tee_dma_heap, kref);



	h->pool->ops->destroy_pool(h->pool);

	tee_device_put(h->teedev);

	h->pool = NULL;

	h->teedev = NULL;

}



static void put_tee_heap(struct tee_dma_heap *h)

{

	kref_put(&h->kref, tee_heap_release);

}



static void get_tee_heap(struct tee_dma_heap *h)

{

	kref_get(&h->kref);

}



static int copy_sg_table(struct sg_table *dst, struct sg_table *src)

{

	struct scatterlist *dst_sg;

	struct scatterlist *src_sg;

	int ret;

	int i;



	ret = sg_alloc_table(dst, src->orig_nents, GFP_KERNEL);

	if (ret)

		return ret;



	dst_sg = dst->sgl;

	for_each_sgtable_sg(src, src_sg, i) {

		sg_set_page(dst_sg, sg_page(src_sg), src_sg->length,

			    src_sg->offset);

		dst_sg = sg_next(dst_sg);

	}



	return 0;

}



static int tee_heap_attach(struct dma_buf *dmabuf,

			   struct dma_buf_attachment *attachment)

{

	struct tee_heap_buffer *buf = dmabuf->priv;

	struct tee_heap_attachment *a;

	int ret;



	a = kzalloc(sizeof(*a), GFP_KERNEL);

	if (!a)

		return -ENOMEM;



	ret = copy_sg_table(&a->table, &buf->table);

	if (ret) {

		kfree(a);

		return ret;

	}



	a->dev = attachment->dev;

	attachment->priv = a;



	return 0;

}



static void tee_heap_detach(struct dma_buf *dmabuf,

			    struct dma_buf_attachment *attachment)

{

	struct tee_heap_attachment *a = attachment->priv;



	sg_free_table(&a->table);

	kfree(a);

}



static struct sg_table *

tee_heap_map_dma_buf(struct dma_buf_attachment *attachment,

		     enum dma_data_direction direction)

{

	struct tee_heap_attachment *a = attachment->priv;

	int ret;



	ret = dma_map_sgtable(attachment->dev, &a->table, direction,

			      DMA_ATTR_SKIP_CPU_SYNC);

	if (ret)

		return ERR_PTR(ret);



	return &a->table;

}



static void tee_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,

				   struct sg_table *table,

				   enum dma_data_direction direction)

{

	struct tee_heap_attachment *a = attachment->priv;



	WARN_ON(&a->table != table);



	dma_unmap_sgtable(attachment->dev, table, direction,

			  DMA_ATTR_SKIP_CPU_SYNC);

}



static void tee_heap_buf_free(struct dma_buf *dmabuf)

{

	struct tee_heap_buffer *buf = dmabuf->priv;



	buf->heap->pool->ops->free(buf->heap->pool, &buf->table);

	mutex_lock(&buf->heap->mu);

	put_tee_heap(buf->heap);

	mutex_unlock(&buf->heap->mu);

	kfree(buf);

}



static const struct dma_buf_ops tee_heap_buf_ops = {

	.attach = tee_heap_attach,

	.detach = tee_heap_detach,

	.map_dma_buf = tee_heap_map_dma_buf,

	.unmap_dma_buf = tee_heap_unmap_dma_buf,

	.release = tee_heap_buf_free,

};



static struct dma_buf *tee_dma_heap_alloc(struct dma_heap *heap,

					  unsigned long len, u32 fd_flags,

					  u64 heap_flags)

{

	struct tee_dma_heap *h = dma_heap_get_drvdata(heap);

	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);

	struct tee_device *teedev = NULL;

	struct tee_heap_buffer *buf;

	struct tee_protmem_pool *pool;

	struct dma_buf *dmabuf;

	int rc;



	mutex_lock(&h->mu);

	if (h->teedev) {

		teedev = h->teedev;

		pool = h->pool;

		get_tee_heap(h);

	}

	mutex_unlock(&h->mu);



	if (!teedev)

		return ERR_PTR(-EINVAL);



	buf = kzalloc(sizeof(*buf), GFP_KERNEL);

	if (!buf) {

		dmabuf = ERR_PTR(-ENOMEM);

		goto err;

	}

	buf->size = len;

	buf->heap = h;



	rc = pool->ops->alloc(pool, &buf->table, len, &buf->offs);

	if (rc) {

		dmabuf = ERR_PTR(rc);

		goto err_kfree;

	}



	exp_info.ops = &tee_heap_buf_ops;

	exp_info.size = len;

	exp_info.priv = buf;

	exp_info.flags = fd_flags;

	dmabuf = dma_buf_export(&exp_info);

	if (IS_ERR(dmabuf))

		goto err_protmem_free;



	return dmabuf;



err_protmem_free:

	pool->ops->free(pool, &buf->table);

err_kfree:

	kfree(buf);

err:

	mutex_lock(&h->mu);

	put_tee_heap(h);

	mutex_unlock(&h->mu);

	return dmabuf;

}



static const struct dma_heap_ops tee_dma_heap_ops = {

	.allocate = tee_dma_heap_alloc,

};



static const char *heap_id_2_name(enum tee_dma_heap_id id)

{

	switch (id) {

	case TEE_DMA_HEAP_SECURE_VIDEO_PLAY:

		return "protected,secure-video";

	case TEE_DMA_HEAP_TRUSTED_UI:

		return "protected,trusted-ui";

	case TEE_DMA_HEAP_SECURE_VIDEO_RECORD:

		return "protected,secure-video-record";

	default:

		return NULL;

	}

}



static int alloc_dma_heap(struct tee_device *teedev, enum tee_dma_heap_id id,

			  struct tee_protmem_pool *pool)

{

	struct dma_heap_export_info exp_info = {

		.ops = &tee_dma_heap_ops,

		.name = heap_id_2_name(id),

	};

	struct tee_dma_heap *h;

	int rc;



	if (!exp_info.name)

		return -EINVAL;



	if (xa_reserve(&tee_dma_heap, id, GFP_KERNEL)) {

		if (!xa_load(&tee_dma_heap, id))

			return -EEXIST;

		return -ENOMEM;

	}



	h = kzalloc(sizeof(*h), GFP_KERNEL);

	if (!h)

		return -ENOMEM;

	h->id = id;

	kref_init(&h->kref);

	h->teedev = teedev;

	h->pool = pool;

	mutex_init(&h->mu);



	exp_info.priv = h;

	h->heap = dma_heap_add(&exp_info);

	if (IS_ERR(h->heap)) {

		rc = PTR_ERR(h->heap);

		kfree(h);



		return rc;

	}



	/* "can't fail" due to the call to xa_reserve() above */

	return WARN_ON(xa_is_err(xa_store(&tee_dma_heap, id, h, GFP_KERNEL)));

}



int tee_device_register_dma_heap(struct tee_device *teedev,

				 enum tee_dma_heap_id id,

				 struct tee_protmem_pool *pool)

{

	struct tee_dma_heap *h;

	int rc;



	if (!tee_device_get(teedev))

		return -EINVAL;



	h = xa_load(&tee_dma_heap, id);

	if (h) {

		mutex_lock(&h->mu);

		if (h->teedev) {

			rc = -EBUSY;

		} else {

			kref_init(&h->kref);

			h->shutting_down = false;

			h->teedev = teedev;

			h->pool = pool;

			rc = 0;

		}

		mutex_unlock(&h->mu);

	} else {

		rc = alloc_dma_heap(teedev, id, pool);

	}



	if (rc) {

		tee_device_put(teedev);

		dev_err(&teedev->dev, "can't register DMA heap id %d (%s)\n",

			id, heap_id_2_name(id));

	}



	return rc;

}

EXPORT_SYMBOL_GPL(tee_device_register_dma_heap);



void tee_device_put_all_dma_heaps(struct tee_device *teedev)

{

	struct tee_dma_heap *h;

	u_long i;



	xa_for_each(&tee_dma_heap, i, h) {

		if (h) {

			mutex_lock(&h->mu);

			if (h->teedev == teedev && !h->shutting_down) {

				h->shutting_down = true;

				put_tee_heap(h);

			}

			mutex_unlock(&h->mu);

		}

	}

}

EXPORT_SYMBOL_GPL(tee_device_put_all_dma_heaps);



int tee_heap_update_from_dma_buf(struct tee_device *teedev,

				 struct dma_buf *dmabuf, size_t *offset,

				 struct tee_shm *shm,

				 struct tee_shm **parent_shm)

{

	struct tee_heap_buffer *buf;

	int rc;



	/* The DMA-buf must be from our heap */

	if (dmabuf->ops != &tee_heap_buf_ops)

		return -EINVAL;



	buf = dmabuf->priv;

	/* The buffer must be from the same teedev */

	if (buf->heap->teedev != teedev)

		return -EINVAL;



	shm->size = buf->size;



	rc = buf->heap->pool->ops->update_shm(buf->heap->pool, &buf->table,

					      buf->offs, shm, parent_shm);

	if (!rc && *parent_shm)

		*offset = buf->offs;



	return rc;

}

#else

int tee_device_register_dma_heap(struct tee_device *teedev __always_unused,

				 enum tee_dma_heap_id id __always_unused,

				 struct tee_protmem_pool *pool __always_unused)

{

	return -EINVAL;

}

EXPORT_SYMBOL_GPL(tee_device_register_dma_heap);



void

tee_device_put_all_dma_heaps(struct tee_device *teedev __always_unused)

{

}

EXPORT_SYMBOL_GPL(tee_device_put_all_dma_heaps);



int tee_heap_update_from_dma_buf(struct tee_device *teedev __always_unused,

				 struct dma_buf *dmabuf __always_unused,

				 size_t *offset __always_unused,

				 struct tee_shm *shm __always_unused,

				 struct tee_shm **parent_shm __always_unused)

{

	return -EINVAL;

}

#endif



static struct tee_protmem_static_pool *

to_protmem_static_pool(struct tee_protmem_pool *pool)

{

	return container_of(pool, struct tee_protmem_static_pool, pool);

}



static int protmem_pool_op_static_alloc(struct tee_protmem_pool *pool,

					struct sg_table *sgt, size_t size,

					size_t *offs)

{

	struct tee_protmem_static_pool *stp = to_protmem_static_pool(pool);

	phys_addr_t pa;

	int ret;



	pa = gen_pool_alloc(stp->gen_pool, size);

	if (!pa)

		return -ENOMEM;



	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);

	if (ret) {

		gen_pool_free(stp->gen_pool, pa, size);

		return ret;

	}



	sg_set_page(sgt->sgl, phys_to_page(pa), size, 0);

	*offs = pa - stp->pa_base;



	return 0;

}



static void protmem_pool_op_static_free(struct tee_protmem_pool *pool,

					struct sg_table *sgt)

{

	struct tee_protmem_static_pool *stp = to_protmem_static_pool(pool);

	struct scatterlist *sg;

	int i;



	for_each_sgtable_sg(sgt, sg, i)

		gen_pool_free(stp->gen_pool, sg_phys(sg), sg->length);

	sg_free_table(sgt);

}



static int protmem_pool_op_static_update_shm(struct tee_protmem_pool *pool,

					     struct sg_table *sgt, size_t offs,

					     struct tee_shm *shm,

					     struct tee_shm **parent_shm)

{

	struct tee_protmem_static_pool *stp = to_protmem_static_pool(pool);



	shm->paddr = stp->pa_base + offs;

	*parent_shm = NULL;



	return 0;

}



static void protmem_pool_op_static_destroy_pool(struct tee_protmem_pool *pool)

{

	struct tee_protmem_static_pool *stp = to_protmem_static_pool(pool);



	gen_pool_destroy(stp->gen_pool);

	kfree(stp);

}



static struct tee_protmem_pool_ops protmem_pool_ops_static = {

	.alloc = protmem_pool_op_static_alloc,

	.free = protmem_pool_op_static_free,

	.update_shm = protmem_pool_op_static_update_shm,

	.destroy_pool = protmem_pool_op_static_destroy_pool,

};



struct tee_protmem_pool *tee_protmem_static_pool_alloc(phys_addr_t paddr,

						       size_t size)

{

	const size_t page_mask = PAGE_SIZE - 1;

	struct tee_protmem_static_pool *stp;

	int rc;



	/* Check it's page aligned */

	if ((paddr | size) & page_mask)

		return ERR_PTR(-EINVAL);



	if (!pfn_valid(PHYS_PFN(paddr)))

		return ERR_PTR(-EINVAL);



	stp = kzalloc(sizeof(*stp), GFP_KERNEL);

	if (!stp)

		return ERR_PTR(-ENOMEM);



	stp->gen_pool = gen_pool_create(PAGE_SHIFT, -1);

	if (!stp->gen_pool) {

		rc = -ENOMEM;

		goto err_free;

	}



	rc = gen_pool_add(stp->gen_pool, paddr, size, -1);

	if (rc)

		goto err_free_pool;



	stp->pool.ops = &protmem_pool_ops_static;

	stp->pa_base = paddr;

	return &stp->pool;



err_free_pool:

	gen_pool_destroy(stp->gen_pool);

err_free:

	kfree(stp);



	return ERR_PTR(rc);

}

EXPORT_SYMBOL_GPL(tee_protmem_static_pool_alloc);

drivers/tee/tee_private.h

+6 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/cdev.h>

#include <linux/completion.h>

#include <linux/device.h>

#include <linux/dma-buf.h>

#include <linux/kref.h>

#include <linux/mutex.h>

#include <linux/types.h>
@@ -24,4 +25,9 @@ struct tee_shm *tee_shm_alloc_user_buf(struct tee_context *ctx, size_t size); 
struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx,

					  unsigned long addr, size_t length);



int tee_heap_update_from_dma_buf(struct tee_device *teedev,

				 struct dma_buf *dmabuf, size_t *offset,

				 struct tee_shm *shm,

				 struct tee_shm **parent_shm);



#endif /*TEE_PRIVATE_H*/